Mustang and Ford Performance Forums banner
1 - 20 of 20 Posts

·
Registered
Joined
·
215 Posts
Discussion Starter · #1 ·
Maybe someone has done this or someone can think of a reason why not to do it.
So here is the idea. I figured out (if my math is right) that if you run twin 255lph pumps in a return style and drive the car for 1 hour. You will have sent and returned 134 gallons (roughly 9 tanks of gas) to the engine and back to the tank. Why not run the engine when not under heavy load/boost on one pump and put the second pump on a hobbs switch with a relay. Like the way a BAP is activated. Advantage is keeps fuel cooler by only returning 1/2 the amount and less pump noise created in the tank. Also not having to use smaller pumps with a BAP like I'm doing now.

Dan
 

·
Registered
Joined
·
4,522 Posts
You could possibly have the Hobbs switch fail to activate at WOT, and hello holes in pistons.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #3 ·
I agree it's the same risk as with running a BAP when boost referenced. I still feel it's a more simple and efficient way to get the job done. I cruise my car more than it's at WOT. I don't want to be moving that much fuel all the time when I don't need to.
I also think if it didn't come on the car would pretty much fall on it's face and I would have enough sence to lift before any real serious damage would occur.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #5 ·
Cool thanks Greg, I'm going to do it. I'm also thinking about wiring in a LED in the circuit and putting it in or near the cluster to come on when the circuit is complete. This way I have a visual the switch is working.
 

·
Administrator
1965 SPF 427 Cobra, & 2022 BMW M850
Joined
·
9,484 Posts
...Why not run the engine when not under heavy load/boost on one pump and put the second pump on a hobbs switch with a relay. Like the way a BAP is activated.
Dan
Dan,

A pump controller might give you more modulation.

Your concerns about the problems associated with large amounts of fuel being bypassed at part throttle are valid. The continual recycling through the pumps and then the bypass circuit raises the fuel temperature. Gas begins to boil at 95 degrees which is why we all used cool cans in the old days. It still boils at 95 degrees today which is why you want to match the fuel delivery curve as close to the engine requirements as possible.

The simplicity of the return style fuel system is seductive. The challenge is what to do with all the fuel when you are not at full throttle. The idea you have is good and a step in the right direction but still leaves a lot of fuel on the table so to speak. The use of a pump controller will allow you to more closely match the fuel delivery to the engine's appetite at any given RPM.

There are a number of very good units available today. I think you will be quite happy with the result.

Ed
 

·
doing it with a 2v..
Joined
·
2,589 Posts
any reccomendations on pump controllers?
 

·
Administrator
1965 SPF 427 Cobra, & 2022 BMW M850
Joined
·
9,484 Posts

·
Registered
Joined
·
215 Posts
Discussion Starter · #9 ·
Ed
The FPSC seems like a good unit/idea. Although the description states the voltage is PWM. From what I understand a return style pump needs a constant B+ voltage or it will burn up very quickly. So a returnless pump like the GT/Focus pump should be used. The FPSC seems like a it does the same thing a FPDM does, but uses rpm as a referance. So by the time you are done you have a hybrid return/returnless system.
Ed thank you for the advise. I think the FPSC would work well, but I'm trying to keep things simple. I may end up going that route once I try this out afterall.
I thought of another potential problem also. I'm using the FORE hate with the single -8 outlet. Both pumps feed into the bottom of the hat and leave out the single -8. I wonder if I will loose some fuel from it bleeding out/pushing out the second pump thats off. I could see that being a big problem. Where it would be better to go with the FPSC. I have twin walbro 190lph pumps now and they hold press for a pretty long time after I turn the key off.

Thanks
Dan
 

·
Administrator
1965 SPF 427 Cobra, & 2022 BMW M850
Joined
·
9,484 Posts
Ed
The FPSC seems like a good unit/idea. Although the description states the voltage is PWM. From what I understand a return style pump needs a constant B+ voltage or it will burn up very quickly. So a returnless pump like the GT/Focus pump should be used. The FPSC seems like a it does the same thing a FPDM does, but uses rpm as a referance. So by the time you are done you have a hybrid return/returnless system.
Ed thank you for the advise. I think the FPSC would work well, but I'm trying to keep things simple. I may end up going that route once I try this out afterall.
I thought of another potential problem also. I'm using the FORE hate with the single -8 outlet. Both pumps feed into the bottom of the hat and leave out the single -8. I wonder if I will loose some fuel from it bleeding out/pushing out the second pump thats off. I could see that being a big problem. Where it would be better to go with the FPSC. I have twin walbro 190lph pumps now and they hold press for a pretty long time after I turn the key off.

Thanks
Dan
Dan,

I agree with you. In the end you have a hybrid system although it should be pretty nice on the street at any throttle position. Without talking to Aeromotive and Walbro I would read the fuel pump suitability tea leaves exactly the same as you did.

With a Fore hat (which I love and use) the second or third pumps have to all work in unison or I believe you are correct the pump which is not running will leak fuel back to the tank creating a lean condition. Using individual PPRVs for each pump might fix the problem but PPRVs introduce a whole set of their own problems.

That plumbing leak/return conundrum through the non running pump is why I was trying to steer you to the pump controller. It operates both pumps in unison eliminating that potentially damaging leak/return path back to the tank.

I'd be interested in knowing how you ultimately sort out the electrical/plumbing logistics.

Regards,

Ed

p.s. Almost forgot. From my understanding also, it appears the controller's triggering event is engine speed as opposed to the 38/40 psi pressure delta a returnless system uses as its triggering event.
 

·
Registered
Joined
·
889 Posts
I Put The Old Walbros 255 Intank Pumps ( WALBROS FOR THE OLD 5.0'S) In My Buddies Cobra. Took Out The Stockers, Put 2 Wablro 255's,2 Dash 6 Fittings, 2 Dash 6 Lines From Tank To (y) Block-filter,then Dash 8 To Regulator, Then Dash 6 Back To Tank. Run Both Pumps On Relays, All Time. No More Fpdm,frps,stock Fuel Lines,stock Fuel Rails,and Most Important-no Computer Playing With Me. 45 Psi All Time. This Was A. Cheap, B. Quite, C. Reliable. You Never Need A Pump Controller, They Run Perfect And Last Forever.
 

·
Registered
Joined
·
496 Posts
Dan,
GSS342s have a check valve on the outlet, so they will hold pressure when off. When you turn off the car, the pressure bleeds off through your regulator. Indeed, if you ever lose one pump, you will probably never know it. (until you run it, then you'll know)

Turbine style pumps, such as the GT pumps, do not have a check valve on the outlet...you'll be lucky to get 20-25 psi on the system with one pump off.

I am a believer in some sort of method to reduce energy going to the pumps when you don't need it, whether it is turning off pumps or voltage reduction. However, running a pair of GSS series pumps full time is a proven setup.

On a side note, we're about to release our regulator that will send a warning signal when the bypass closes. (to signal the pumps are maxed, can be wired to a warning light, for example)

Justin
 

·
Registered
Joined
·
889 Posts
dan,
Gss342s Have A Check Valve On The Outlet, So They Will Hold Pressure When Off. When You Turn Off The Car, The Pressure Bleeds Off Through Your Regulator. Indeed, If You Ever Lose One Pump, You Will Probably Never Know It. (until You Run It, Then You'll Know)

Turbine Style Pumps, Such As The Gt Pumps, Do Not Have A Check Valve On The Outlet...you'll Be Lucky To Get 20-25 Psi On The System With One Pump Off.

I Am A Believer In Some Sort Of Method To Reduce Energy Going To The Pumps When You Don't Need It, Whether It Is Turning Off Pumps Or Voltage Reduction. However, Running A Pair Of Gss Series Pumps Full Time Is A Proven Setup.

On A Side Note, We're About To Release Our Regulator That Will Send A Warning Signal When The Bypass Closes. (to Signal The Pumps Are Maxed, Can Be Wired To A Warning Light, For Example)

Justin
Is This Warning Signal Part Of The Reg? Or Is It Something We Can Add To Ours, Like 1/8 Npt? And At What Pressure Does It Go Off?
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #14 · (Edited)
Justin, thanks soo much for clearing that up about how the fuel press bleeds off.

Nitros, I would guess that the reg should always be bypassing some amount of fuel even when regulating at WOT. So if it closes completely that means you have maxed out the pumps. This would cause a light to come on as a warning. If you we talking returnless terms you could say the pumps are at 100% duty cycle. You probably already know that but I guess that's kinda how their reg would work.
 

·
Registered
Joined
·
496 Posts
Dan,
That is exactly how the warning will work..it is a switch that closes when the regulator stops bypassing fuel. This way you don't have to count on keeping an eye on the gage. Also, if you have a failure in a pump/controller/BAP/switch/whatever, you'll know it as soon as the fuel system isn't keeping up with the motor. This is becoming more important as fuel systems inevitably become more complex. Nowadays, 600 rwhp on a street cars is fairly routine...and that number will be left in the dust in the time to come.
 

·
Registered
Joined
·
323 Posts
Dan, could you provide an update please ? I'm getting ready to install my fuel setup and seriously considering a Hobbs switch on my twin GSS342 setup. What did you end up doing ?

I would also like to commend Justin on his regulator idea, seems like another awesome product in the making !

Alex
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #17 ·
Motor just came back from machine shop will be a few weeks until it's back in and running.

This is how I'm going to control them. Right now I have a single 8 guage wire feeding two seporate relays for power. One relay for each pump. The control for the relay is off the power wire to the fpdm. So the ignition (key on) controls the power/ground to relays. I'm going to cut the gound to one of the relays and splice in the wires from the hobbs switch. This will allow only one pump to run until in boost. Then the hobbs switch will close, complete the circuit to ground and active the second pump.

I'm also going to wire in a LED in or near the cluster to come on when the circuit is complete. To act as a visual to let me know the pump is on.

I'll take some pics and post them up when I get closer to finshed.

Dan
 

·
Registered
Joined
·
5,237 Posts
I run 3 GSL392(255 Walbro's)

I have 2 running full time and the 3rd pump is kicked on under 9psi of boost. I wanted to always run 2 pumps full time just incase something happens vs running 1 full time and 2 coming on under boost.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #19 ·
I live in Raleigh NC and plan on cruising my car when done back home to Chicago to visit with friends and family. It's 900 miles one way. Should be over 2k trip when finished. It will see alot of time under 1/2 tank and I think having only one pump running will help out considerable in keeping fuel temps down when cruising.
 

·
Registered
Joined
·
5,237 Posts
I live in Raleigh NC and plan on cruising my car when done back home to Chicago to visit with friends and family. It's 900 miles one way. Should be over 2k trip when finished. It will see alot of time under 1/2 tank and I think having only one pump running will help out considerable in keeping fuel temps down when cruising.
If you are very worried about fuel temperatures Glenn's does have a large fuel cooler that you can buy and plumb into the system.

Something to think about also.
 
1 - 20 of 20 Posts
Top